Sheridan Window Cleaners monthly income statement at several levels of activity is as follows:

Windows washed 2,500 4,300 9,800

Sales revenue $ 3,900 $ 6,708 $ 15,288

Cost of goods sold 1,300 2,236 5,096

Gross profit 2,600 4,472 10,192

Operating expenses

Advertising expense 400 400 400

5000 windows

Salaries and wages expense 750 930 1,480

Insurance expense 200 200 200

Postage expense 400 688 1,568

Total operating expense 1,750 2,218 3,648

Operating income $ 850 $ 2,254 $ 6,544